Lampard has confirmed that Christian Pulisic is out for a few weeks with abductor problem.
The Blues boss told a press conference on Friday: "Pulisic is out, he will be out for a few weeks. Adductor injury. It's disappointing for us and we will have to see how quickly he recovers because it is quite a nasty injury.
"It is a damaging miss. Before Christmas, he did report a bit of tiredness so he came out of the team and I was worried about injury.
"He is a very talented player, where he can make things happen."
Lampard also delivered an update on Ruben Loftus Cheek - who has yet to feature for Chelsea this season - as he continues to recover from a serious Achilles injury.
"He [Loftus Cheek] is out, still for a while. We are hoping we can get him doing collective training at some point, maybe with the academy," he said.